Weekend house up to 150 k€ in BB

I was referring to the fact that I am not allowed to simply park the motorhome on the still empty plot and then spend the night there. For that, you would probably need

1. a parking space on the property
2. overnight stays would not be permitted

I would check that statement again. Overnight stays in the motorhome on your own property are not a problem, only possibly permanent residence. Depending on the length of your stays, that is a possible solution. A nice garage barn for it, and done. We often stay overnight on private land in the motorhome (just a panel van). It’s the perfect way to visit friends. No return trip, no effort for the hosts, no agreement about who gets tired when…

I would double-check this statement. Overnight stays in the motorhome on your own property are no problem, only possibly permanent living. Depending on the length of your stays, that is a possible solution. A nice garage barn to go with it, and done. We often stay overnight on private land in the motorhome (just a van). It's the perfect way to visit friends. No drive home, no effort for the hosts, no agreement about who gets tired when…

I will ask again, but unfortunately I have already brought up this subject several times. You would need a registered parking space (which would probably only be located at the property boundary) and as soon as you stay in it overnight it becomes living space that requires a building permit. It seems to me it might soon be more practical to just "do it." Does a building only used temporarily actually have to comply with the Energy Saving Ordinance? I am thinking of simple log cabins or solidly built small houses. Heated with a fireplace and infrared for frost protection.

Question about "how long am I allowed to stay with a motorhome on my own property autark?". For that, you don’t need a pitch with supply and disposal. The bottleneck is always the toilet; gas, electricity, water, and wastewater are no problem in the motorhome for over a week if appropriately equipped. If you build a “cabin” with supply, you don’t have the energy-saving ordinance regulations and still have a toilet and possibly a shower; electricity from the cable reel is not a problem and advantageous for the fridge, which then does not have to run on gas.

What is your current status?

however, no matter how rarely you want to use it, always fully observe the valid thermal protection standard as for year-round houses.

I think
Building Energy Act § 2 Scope
(1) ...
(2) With the exception of §§ 74 to 78, this law does not apply to
...
8. Residential buildings that
a) are intended for a usage period of less than four months annually or
b) are intended for a limited annual usage period and whose expected energy consumption for the limited annual usage period is less than 25 percent of the expected energy consumption with year-round use, and
...

the §§ 74 to 78 concern the "Energy inspection of air conditioning systems" – so they should be irrelevant for a weekend house without air conditioning

what justifies your differing assessment here?

Why does one buy or want to buy a very large plot of land in a residential area ... to spend holidays there?

I will look at an 800 sqm plot this weekend ... in Kafflage and developed with an old barn ...

The land value according to the "official" standard land value would be 24 k€ - the asking price is 35 k€ above that (however explicitly as a "negotiation basis")

I would only want to use it as a "dacha" and not as a sole/main residence
(with the ground floor of the barn as a garage for the car not currently in use - sometimes the everyday car/sometimes the campervan, for a small workshop corner and as storage space)